JP3414155B2 - Leak tester and leak test method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak tester and a leak test method for detecting casting defects such as cavities and cracks in cast products, and mounting defects of seal parts.

[0002]

2. Description of the Related Art Generally, a leak test is carried out in order to inspect whether a crack or a hole is formed in a work. For the conventional leak test, for example,
There is a technique disclosed in No. 19431. That is, in such a leak test method, the inside of the work is pressurized or depressurized, the inside of the work is set to a desired test pressure, the inside of the work is closed, and the pressure fluctuation in the work thereafter is measured by a pressure gauge. If the pressure fluctuation is different from that of the work, the work is judged to be abnormal because it has a defective portion such as a crack or a hole.

[0003]

In the above-mentioned leak test method, in the case of a work made of one part such as a container to which accessory parts are not attached or a cast part body, the defect of the work should be properly detected. Is possible. However, it is difficult to satisfactorily detect defects in a work piece in which some parts are assembled. For example, in the case of a work such as a pump, in addition to some parts for realizing the main function of the pump, a seal member for preventing oil leakage inside the pump is installed in the work body which is a casting part. Is configured. In the case of such a work, it is necessary to detect two types of abnormalities, that is, whether the seal member is defective or not, in addition to the defect during the casting of the work body. It is difficult to detect such an abnormality of the seal member in the above-mentioned conventional technique.

When the work is a pump or the like, various inspections other than the leak test are performed to determine the quality of the product. It is natural to improve the accuracy of such various inspections, but on the other hand, there is a demand for downsizing of the apparatus used for the inspection and reduction of the inspection time. The present invention has been made in order to solve such a problem, and causes both abnormalities of defects of a cast or injection-molded work body part and defects of a mounting member such as a seal member attached to the work. An object of the present invention is to provide a leak tester and a leak test method that can detect and reduce the size of the entire inspection apparatus including the inspection steps other than the leak test, and shorten the inspection time.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems.
The pressure supply source pressurizes or depressurizes the inside of the work,
The pressure inside the workpiece can be detected by a pressure sensor.
Therefore, a leak test is performed to judge whether the work is tightly sealed.
In the strike method, the workpiece is supplied by the pressure source.
After pressurizing or depressurizing the inside in a pulse,
Part is continuously pressurized or depressurized, and
The pressure was increased or decreased to the set pressure.
After that, the pressure inside the work is measured by the pressure sensor.
Then, the quality of the work is judged based on this measurement result.
Repeat the set cycle twice before the second cycle
The set pressure is lower than the set pressure in the first cycle.
It is characterized by high pressure.

According to a second aspect of the present invention, the first and second minor
The first port of a work having at least two ports
A pressure supply source connected via a switching valve for pressurization to
Connected to the second port of the workpiece via the exhaust switching valve.
And a switching valve for pressurizing the workpiece and the first
It is installed between 1 port and measures the pressure inside the work.
Pressure sensor, the pressurization switching valve, and the discharge switching
A valve and a controller for controlling the pressure sensor
It is a leak tester, wherein the control device is configured to cut off the pressure.
Open the switching valve and the exhaust switching valve, and
Liquid remaining in the work due to pressure from the supply source
Liquid draining means for discharging to the discharge part and the pressurization switching
The valve is opened and the exhaust switching valve is closed.
The inside of the work is pressurized by the pressure from the pressure supply source.
The pressurizing means and the inside of the work are roughened by the pressurizing means.
After the pressure has been set by caulking, close the switching valve for pressurization.
By the pressure balance means to be in a state and this pressure balance means
The pressure in the sealed work is measured by the pressure sensor.
Based on the measurement results of this measuring means
And a determination means for determining the quality of the work.
It is a thing.

[0007]

(Operation) The device according to claim 1 operates at a low pressure.
After the first cycle performed, a second cycle at high pressure
Do As a result, in the first cycle, mainly
Inspect the seal members inside the slab and
Kuru mainly inspects the work body.

[0009] as described in claim 2, the pressurizing switching valve and the switching valve for exhaust and an open state, by supplying the pressure to the pressure source or Lawah over the click, the liquid remaining in the work Discharge to the discharge part. Thereafter, the pressurizing switching valve is opened and the exhaust switching valve is closed to pressurize the inside of the work by the pressure from the pressure supply source. As a result, the pressure in the work is set to a preset pressure, the pressurizing switching valve is closed, and the pressure in the sealed work is measured by the pressure sensor. The quality of the work is determined based on the measurement result.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The first leak tester of the present invention will be described below.
The embodiment will be described with reference to FIG. The work W of the present embodiment is a hydraulic pump, and the leak test of the work W is performed after actually assembling hydraulic pressure to the assembled hydraulic pump and checking whether the pump is functioning normally. Is. Therefore, the leak tester according to the present embodiment is configured such that the oil test process for removing the oil remaining in the work W in the previous process and the leak test can be continuously performed by the same device.

In FIG. 1, a pressurized air source 20 and a work W
Are connected by a piping line 21 composed of an oil resistant hose. The pressurized air supply source 20 is a pressurized air tank,
Pressurized air can always be supplied. Work W
Is a state in which a seal member Wb for preventing oil leakage and the like is assembled inside the main body Wa which is a cast product. The work W and the piping line 21 are the main piping 2 described later.
1c and the discharge port Wp1 side of the pump are connected via a coupler 32, and a discharge pipe 21d described later and a suction port Wp2 side of the pump are connected via a coupler 33.

A pressurized air source 20 is attached to an upstream end of the piping line 21, and the piping line 21 is connected to the pressurized air source 20 and then two branch pipings 21 are connected.
It is branched into a and 21b, integrated again into the main pipe 21c, and connected to the work W through the coupler 32. The pressurized air sealed in the work W is discharged from the coupler 33 via the discharge pipe 21d.

A low-pressure regulator 22 for reducing the pressure of the pressurized air from the pressurized air source 20 to a first set pressure as a low pressure is attached to the branch pipe 21a, and is provided between the low-pressure regulator 22 and the main pipe 21c. The first pressurizing solenoid valve 2
4 are provided. The first pressurizing solenoid valve 24 is turned on and off by a control signal from the controller 40. A method of supplying pressurized air in a pulsed manner by periodically turning on and off, and an on state. By maintaining the above, it is possible to selectively perform the method of constantly supplying the pressurized air.

Similarly, in the branch pipe 21b, the pressurized air from the pressurized air source 20 has a second pressure higher than the first set pressure.
A high pressure regulator 23 for reducing the set pressure is attached, and a second pressurizing solenoid valve 25 is provided between the high pressure regulator 23 and the main pipe 21c. This second
The pressurizing solenoid valve 25 can selectively perform a method of supplying pressurized air in a pulsed manner and a method of constantly supplying pressurized air similarly to the first pressurizing solenoid valve 24. Has become.

A pressure sensor 26 for detecting the pressure inside the work W is arranged in the main pipe 21c. A pressure switch 31 is attached at a position facing the pressure sensor 26. The operating pressure of the pressure switch 31 is
The pressure is set to be lower than the first set pressure for pressurizing the work W. Therefore, this pressure switch 31
Indicates that the pressure does not rise even when the system is operated, and there is a large problem in the airtightness of the work W, or the couplers 32 and 33 connecting the work W and the piping line 21 are not connected. It indicates that it is not installed correctly. In addition, this pressure switch 3
1 is not an indispensable requirement because the purpose is to improve the certainty of workability.

An exhaust electromagnetic valve 29 is provided in the exhaust pipe 21d, and the pressurized air supplied to the work W is opened to the atmosphere by operating the exhaust electromagnetic valve 29. . Note that, as described above, in the present embodiment, the oil draining process of the work W is also used, and therefore, the end of the exhaust pipe 21d is connected to the tank 34 (discharging portion) for storing the discharged oil.

The above-mentioned first and second pressurizing solenoid valves 24, 2
5, the exhaust solenoid valve 29 and the pressure switch 31 are connected to the controller 40, and the controller 40
These electrical controls such as sequence control are performed. The pressure sensor 26 is also connected to the sensor controller 30. Sensor controller 30
Is for determining the quality of the work W based on the output result of the pressure sensor 26, and the detection result can be displayed on the display screen 30a. Controller 40
And the sensor controller 30 are connected so that a measurement start signal from the pressure sensor 26 and the like can be transmitted and received.

Next, the operation will be described. In the inspection of the work W in the present embodiment, first, the oil in the work W is removed,
Next, a leak test is conducted. FIG. 2 is a flowchart showing an outline of the oil removing process. In the initial state before the inspection of the work W, all the solenoid valves 24, 25, 29 are inactive. In this state, the worker connects the work W and the piping line 21 with the couplers 32 and 33.

In step 100, the exhaust electromagnetic valve 29 is operated so that the oil remaining in the work W can be discharged to the tank 34. Then, in step 102, the second pressurizing solenoid valve 25 is actuated so that pressurized air can be supplied from the branch pipe 21b side. In step 104, the second
The solenoid valve 25 for pressurization is maintained in the ON state for a certain period of time, and pressurized air is constantly supplied to the work W. As a result, the oil remaining in the work W is discharged to the tank 34.

When the supply of the pressurized air for a certain period of time is completed, the second pressurizing solenoid valve 25 is turned off in step 106 to shut off the supply of the pressurizing air, and then the exhaust solenoid valve 29 is turned on in step 108. Turns off and returns to the initial state. Then, the leak test is started (step 110). The leak test is a first cycle in which the low pressure is mainly used to determine whether the sealing property of the seal member Wb is good or bad, and a high pressure is mainly in which the quality of the main body Wa is determined to be good or bad, that is, the porosity, cracks or the like generated during casting. It consists of 2 cycles. Each cycle includes a pulse pressurization process, a constant pressurization process, an equilibrium process, a determination process, and an exhaust process. When the leak test is started, it is in the initial state described above.

FIG. 3 is a diagram showing an outline of this embodiment, and FIG. 4 is a flow chart showing the first cycle. In step 200, the first pressurizing solenoid valve 24 is intermittently turned on and off a predetermined number of times to supply the pressurized air from the pressurized air source 20 in a pulsed manner (pulse pressurizing step). At this time, the low-pressure regulator 22 supplies the work W with the first set pressure of the low-pressure pressurized air in a pulsed manner. By this pulsed pressurization, the seal member Wb attached to the work W is intermittently pressed and spread. Therefore, if the seal member Wb is not properly attached or if the seal member Wb itself has a defect, air leakage is further increased, and the defect is easily detected. Further, when foreign matter such as chips is caught in the seal member Wb, it also has an action of removing them.

After performing such pulsed pressurization for a certain period of time, the routine proceeds to step 202, where the first pressurizing solenoid valve 24 is maintained in the ON state, and the pressure of the pressurized air source 20 is kept constant. Supply pressurized air (constant pressure process). When the pressurized air is supplied for a certain time, the inside of the work W is pressurized to the first set pressure (step 204). After this, step 2
At 06, the first pressurizing solenoid valve 24 is closed to seal the inside of the work W (equilibrium process). Then, in step 208, the pressure sensor 26 is reset, and the amount of decrease in pressure is measured in step 212, which will be described later, with the pressure at this time as a reference. In this way, the work W is hermetically sealed, and the equilibrium state is maintained for a predetermined time in step 210, and then the pressure is detected in step 212 (determination step).
If there is a problem with the tightness of the work W, the pressurized air will leak more than the allowable amount during the equilibrium time of step 210, and the pressure will drop more than the allowable value. Therefore, if the value of the pressure sensor 26 at this time is not within the predetermined allowable range, it means that the work W is defective.

In step 214, the pressure sensor 26
If the value is within a predetermined allowable range and the inspection result is good (YES), the process proceeds to step 216, and the fact that the inspection is passed is displayed on the display screen 30a of the sensor controller 30. Then, in step 218, the exhaust electromagnetic valve 29 is operated to release the pressurized air in the work W (discharging step). After the pressurized air has been released for a certain period of time, the exhaust electromagnetic valve 29 is closed, the routine proceeds to step 220, and the routine proceeds to the second cycle.

On the other hand, in step 214, if the value of the pressure sensor 26 is out of the predetermined allowable range and the inspection result is defective (NO), the process proceeds to step 222, and the sensor controller 30 displays that the inspection has failed. Display on the screen 30a. Then, similarly to step 218, the pressurized air in the work W is released in step 224 (discharging step), and the inspection is completed only in the first cycle (step 2).
26).

In this way, if the inspection result is already abnormal in the first cycle, there is a high possibility that a problem has occurred in the seal member Wb, and the worker rechecks the work W focusing on this point. It can be carried out. The flowchart of FIG. 5 shows the second cycle. The first cycle and the second cycle are basically the same except that the set pressure is different. The difference is that in step 300, the solenoid valve that supplies the pressurized air having the second set pressure, which is a high pressure, has the second solenoid valve.
It is only the pressurizing solenoid valve 25, and regardless of whether the work W is passed or failed, after releasing the pressurized air, all the operations are finished. The reason why the pulse pressure is applied in the second cycle is that the seal member Wb is reconfirmed by the high pressure pulse and the foreign matter is removed. Because of
If it is considered sufficient to confirm the seal member Wb in the low-pressure first cycle, it is not necessary to perform pulse pressurization in the second cycle.

FIG. 6 shows a second embodiment of the leak tester of the present invention. The main points different from the first embodiment are, in addition to the pressurized air source 20 that pressurizes the inside of the work W,
The point is that a vacuum pump 50 that makes the inside of the work W a negative pressure is provided. In FIG. 6, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Explaining the parts different from the first embodiment, since the low pressure is applied by the negative pressure by the vacuum pump 50, the branch pipe 21 a
The device for supplying low-pressure pressurized air arranged above is unnecessary. Further, the exhaust electromagnetic valve 51 instead of the exhaust electromagnetic valve 29 is in a non-operating state in which the exhaust pipe 21d is closed,
The vacuum pump 50 and the exhaust pipe 21d are in communication with each other, and the tank 34 and the exhaust pipe 21d are in communication with each other.

Next, the operation will be described. In the second embodiment as well, the oil removing process is performed as in the first embodiment, but the description is omitted because it is basically the same as the process shown in FIG. In the second embodiment, the exhaust electromagnetic valve 51 is used instead of the exhaust electromagnetic valve 29 of the first embodiment to discharge oil to the tank. FIG. 7 is a diagram showing an outline of the leak test of the second embodiment, and FIG. 8 is a flowchart showing the first cycle of the second embodiment. In the leak test of the second embodiment, in the first cycle, the vacuum pump 50 performs air bleeding in a pulsed manner, then the work W is made negative pressure, and the pressure sensor 26 is passed through a negative pressure equilibrium state. Is to inspect the airtightness of the work W.

In step 400, driving of the vacuum pump 50 is started, and the exhaust electromagnetic valve 51 is intermittently turned on and off a predetermined number of times to depressurize the inside of the work W in a pulsed manner from the pressurized air source 20. After performing such pulsed pressure reduction for a certain period of time, the routine proceeds to step 402, where the work W and the vacuum pump 50 are kept connected by the exhaust electromagnetic valve 51. By sucking the air in the work W for a certain period of time, the work W is depressurized to a preset pressure (step 404). Thereafter, in step 406, the exhaust electromagnetic valve 51 is deactivated, and the area from the second pressurizing electromagnetic valve 25 to the exhaust electromagnetic valve 51 is sealed. After that, the operation of the vacuum pump 50 is stopped.

Then, in step 408, the pressure sensor 26
Is reset, and the amount of increase in pressure is measured in step 412 to be described later with reference to the pressure at this time. After the equilibrium state is maintained for a predetermined time in step 410, the pressure is detected in step 412.
If there is a problem with the tightness of the work W, the outside air will flow in more than the allowable amount during the equilibration time, and the pressure will increase more than the allowable value. In step 414, the value of the pressure sensor 26 is within the predetermined allowable range,
If the inspection result is good (YES), the process proceeds to step 416, and the fact that the inspection is passed is displayed on the display screen 30a of the sensor controller 30. Then, in step 418, the exhaust electromagnetic valve 51 is operated to communicate the work W with the atmosphere, then the exhaust electromagnetic valve 51 is closed, the process proceeds to step 420, and the process proceeds to the second cycle.

On the other hand, in step 414, if the value of the pressure sensor 26 is out of the predetermined allowable range and the inspection result is bad (NO), the process proceeds to step 422, and the sensor controller 30 displays that the inspection has failed. Display on the screen 30a. Then, after the work W is communicated with the atmosphere in step 424, the inspection is finished only in the first cycle (step 426).

As described above, in the first cycle of the second embodiment, since the work is pressurized by the negative pressure, the seal member Wa of the work W is deformed in the direction in which it is extended to the inner side of the work. As a result, the foreign matters and the like sandwiched between the seal members Wa are more effectively removed, and the seal members Wb
The defect of can be detected more accurately. Regarding the second cycle of the second embodiment, the first cycle shown in FIG.
Since it is the same as the second cycle of the above embodiment, the description thereof will be omitted.

[0032]

As described above, according to the present invention, in the first aspect, the first cycle at low pressure is
Suitable for inspection of seal members inside work, high pressure
The second cycle by
It is suitable for inspection, so in which cycle an abnormality is detected.
The defective portion of the work can be easily estimated depending on whether or not the work is broken.
Therefore, the inspection time of the work is shortened.

According to the second aspect of the present invention, it remains in the work.
Can be used as a leak test for removing liquid
Therefore, the entire inspection apparatus can be downsized and the cost can be reduced. Well
Also, the inspection time is short because the work piece need only be attached once.
Can be shortened.

[0034]

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart showing an oil removing process of the first embodiment.

FIG. 3 is a diagram showing an outline of a leak test according to the first embodiment.

FIG. 4 is a flowchart showing a first cycle of the first embodiment.

FIG. 5 is a flowchart showing a second cycle of the first embodiment.

FIG. 6 is an overall configuration diagram of a second embodiment of the present invention.

FIG. 7 is a diagram showing an outline of a leak test according to a second embodiment.

FIG. 8 is a flowchart showing a first cycle of the second embodiment.

[Explanation of symbols]

20 pressurized air source 21 Piping line 22 Low pressure regulator 23 High voltage regulator 24 First pressurizing solenoid valve 25 Second pressurizing solenoid valve 26 Pressure sensor 29 Exhaust solenoid valve 30 sensor controller 34 tanks 40 controller W work Wa work body Wb seal member Wp1 discharge port Wp2 suction port

Continued front page       (56) Reference JP-A-2-259439 (JP, A)                 JP-A-2-306133 (JP, A)                 JP-A-6-235680 (JP, A)

Claims (2)

(57) [Claims] 1. The inside of the work is pressurized by a pressure supply source.
Or depressurize and use the pressure sensor to measure the pressure inside the work.
By detecting it, it is possible to judge whether the sealing property of the work is good or bad.
In the leak test method of disconnecting,
Then, the inside of the work was pressurized or depressurized in a pulse shape.
After that, continuously pressurizing or depressurizing the inside of the work,
The inside of the work is pressurized up to the preset pressure.
Or after the pressure is reduced, the pressure inside the work is adjusted to the pressure
Sensor and based on this measurement result
Repeat the cycle to judge the quality of the ark two times
The set pressure of the cycle is the same as that of the first cycle.
Leak test characterized by higher pressure than set pressure
Method. 2. At least two ports, a first and a second port
Through the pressurizing switching valve to the first port of the work that has
Connected pressure supply source and the second port of the workpiece
And a discharge part connected to the
Is provided between the pressurizing switching valve and the first port.
A pressure sensor for measuring the pressure in the work, and
Pressure switching valve, discharge switching valve and pressure sensor
A leak tester having a control device for controlling
The control device includes the pressurizing switching valve and the exhaust switching valve.
Open the valve and open it with the pressure from the pressure source.
Liquid for discharging the liquid remaining in the work to the discharge part
Open the body withdrawal means and the pressure switching valve, and
Close the switching valve for air to the pressure from the pressure supply source.
Therefore, the pressurizing means for pressurizing the inside of the work and the pressurizing hand
The pressure in the work is preset by the step
After that, the pressure balance means for closing the pressurizing switching valve is closed.
And inside the work closed by this pressure balancing means
Measuring means for measuring the pressure of by the pressure sensor,
Based on the measurement result of this measuring means, whether the work is good or bad
Leakage characterized by having a determination means for performing determination
Tester.